Chapter 6: Dominatin Life in Water - The Major Radiation of Fishes Flashcards
What are the two major groups of bony fish?
Ray-finned fish (actinopterygians)
Lobe-finned fish (sarcopterygians)
What is the Devonian also known as?
The Age of Fishes because all major lineages of fishes coexisted
True or false
Bony fish don’t have a gas-filled bladder
FALSE
They do
What are Dipnoi?
Lungfishes
Define paedomorphosis
The appearance of juvenile characters in an adult
True or false
Ray-finned fishes represent the largest radiation of vertebrates
True
True or false
Actinopterygians enlarge their forebrain
True
Why do Actinopterygians enlarge their forebrain?
The combination of a small head size and large eyes may create space-packing problems within the developing head, resulting in their inside-out, large brain development
Why was their a reduction in the heavy armor of Ray-finned fish?
They had more mobile fins which meant they had more versatile locomotion which increased their ability to avoid predators, thus the need to be light
What is the gill cover called?
Operculum
Why is suction important in prey capture in water?
A rapid approach by a predator pushes a wave of water in front of its head toward the prey
True or false
Teleosts have great mobility in the skeletal elements that rim the mouth
True
Why do teleosts have the mobility of the mouth?
It allows the grasping margins of the jaws to be extended forward from the head, often at remarkable speed protrusible jaws
True or false
Protrusion helps in gripping prey
True
How do fish swim?
Swimming results from anterior-to-posterior contractions of the muscle segments along one side of the body and simultaneous relaxation of those of the opposite side
Where does most of the power for swimming come from?
Muscles in the posterior region of the fish
What must fish do to be able to swim?
They must overcome the downward pull of gravity and the drag of water. In order to do this they generate vertical lift (a lot do this by generating buoyancy with a gas-filled swim bladder)
What is viscous drag affected by?
Surface smoothness
What is inertial drag affected by?
Body shape
What are the two major life zones in the sea?
1) Pelagic (where organisms live a free-floating or swimming existence)
2) Benthic (where organisms associate with the bottoms either near shore or at great depths)
What depth is sunlight totally extinguished?
1000 meters
True or false
Fish increase in abundance, size, and species diversity at great depths
FALSE
They decrease
What are the costs and benefits of vertical migration?
Benefits: by rising at dusk, certain fish enter a region of higher productivity where there is more food
Costs: they increase their exposure to predators
When do the Osteichthyes appear in the fossil record?
Late Silurian period
